<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<style type="text/css">
.btn {
      position: absolute;
      top: 50%;
      left: 50%;
      transform: translate(-50%, -50%); /*更改button位置 */
      width: 230px;	/*button宽*/
      height: 90px;	/* button高*/
      line-height: 90px;  /*button文字位置，和height一样是在中间*/
      text-align: center;
      color: #fff;
      font-size: 24px; /*设置button中文字大小 */
      text-transform: uppercase;
      text-decoration: none;
      font-family: sans-serif;
      box-sizing: border-box;
      background: linear-gradient(90deg, #03a9f4, #f441a5, #ffeb3b, #03a9f4);
      background-size: 400%;
      border-radius: 60px; /*设置button四角弧度*/
      z-index: 1;
    }
    
    .btn:hover {
      animation: animate 8s linear infinite;
    }
    
    @keyframes animate {
      0% {
        background-position: 0%;
      }
      100% {
        background-position: 400%;
      }
    }
    
    .btn::before {
      content: '';
      position: absolute;
      top: -5px;
      left: -5px;
      right: -5px;
      bottom: -5px;
      z-index: -1;
      background: linear-gradient(90deg, #03a9f4, #f441a5, #ffeb3b, #03a9f4);
      background-size: 400%;
      border-radius: 40px;
      opacity: 0;
      transition: 0.5s;
    }
    
    .btn:hover::before {
      filter: blur(20px);
      opacity: 1;
      animation: animate 8s linear infinite;
    }
</style>
</head>
<body>
 <a href="#" class="btn">button</a>
</body>
</html>